Hi all. I'm just a SLF normally found lurking and keeping myself to myself because I haven't got any aviation experience or knowledge to share, but I did used to be a Paramedic so have a little relevant information with regards to this thread.
Just to make the point that fixed dilated pupils aren't a sign of brain death, and there is every chance that with prompt defibrillation someone in cardiac arrest and dilated pupils might well be saved. Its been a few years since I've been in the job, but they used to say that for every minute that passes from arresting to defibbing the chances of survival go down by 10%, so even allowing for the time to remove the pilot from the seat in theory you might stand more chance of getting someone back than we did, bearing in mind our sometimes lengthy response times.
Obviously it all depends on why someone arrests and the cardiac arrest rhythm they go into, and they're probably more likely not to survive than be saved, but a younger patient just suddenly dying from nowhere I reakon would probably be the most likely to respond to a defib.
Don't want to sound like I'm saying that this poor guy could have been saved, not talking about him in particular. I've been to dozens of cardiac arrests and only got about 5 back. Just that without trying, you'll never know. Fixed dilated pupils aren't diagnostic of death.